As you can see each time it prints 'Loops' it has done 10,000 data transfers. So it's not slow, as in acoustic modem slow, but it is a clunky way of transferring large amounts of data.

Xena really needs external (to the chip) circuitry to get to the PCIe portion of the Xorro slot for moving data in a more elegant manor. Xena can do the heavy lifting for that but not by herself, and leave the localbus interface for command and control.